1. Field of the Invention
The present invention pertains to the art of dishwashers and, more particularly, to a drain and purge system employed in a dishwasher.
2. Discussion of the Prior Art
In a typical dishwasher, washing fluid is pumped from a sump into upper and lower wash arms such that kitchenware retained on vertically spaced racks within a tub of the dishwasher will be sprayed with the washing fluid for cleaning purposes. The washing fluid is heated, filtered and recirculated. Prior to recirculating the washing fluid, the fluid is directed through one or more filters to remove soil from the fluid, with the soil being collected in a chamber. Periodically, the system will be purged in order to drain the collection chamber of the soil.
In recent years, it has become increasingly common to provide a series of straining or filtering units in connection with an overall dishwasher pumping system such that different sized soil particles are collected at varying locations. For example, a strainer can be employed to retain large soil particles, while a fine filter can be utilized to remove smaller particles. That is, the smaller particles are able to pass through the strainer, which essentially constitutes a first filtering unit, and are caught by the second or fine filter. In connection with the pumping and filtering operation, it is also known to incorporate a mincer or chopper in order to minimize soil particle size, such as just prior to a drainage operation.
Obviously, the ability of the dishwasher to thoroughly clean the kitchenware will depend on a number of factors, including the actual configuration and flow of fluid through the filtering system, as well as the manner in which pumping and draining operations are performed. For instance, as the degree of soil on the kitchenware being cleaned can significantly change between loads, the amount of soil collected in the overall dishwasher pump will be different. Correspondingly, the desirable number of drain or purge operations needed to expel the collected soil can vary. Although various dishwasher pump and filtration systems are known in the art, there still exists a need for improvements in this field in order to further enhance the overall cleaning functions performed by dishwashers, particularly in connection with determining an effective system for providing drain or purging operations based on system dynamics such that an adaptive control is established.